"What they're doing with Greece has a name: terrorism," Varoufakis told the Saturday edition of the Spanish newspaper El Mundo, referring to the International Monetary Fund (IMF), European Central Bank (ECB) and the European Union (EU).

"Why have they forced us to close the banks? To frighten people. And spreading fear is called terrorism," he said, adding that the "troika" of creditors wanted to "humiliate Greeks."

Greeks have been subjected to cash rationing

The government in Athens closed banks and implemented capital controls this week after failing to reach an agreement with creditors last weekend on an extension of its bailout program. It has promised that the banks will re-open on Monday.

However, Varoufakis said he was sure an agreement would be reached even if Greeks vote against a new bailout offer proposed by creditors in June at the referendum on Sunday.

When asked why, he said failing to reach an agreement would be too costly for both sides.

"If Greece crashes, a trillion euros will be lost. It's too much money and I don't believe Europe could allow it," Varoufakis said.

Too close to call

Sunday's referendum will ask Greeks to vote on whether or not to accept the new bailout offer, which is rejected by the government under Prime Minister Alexis Tsipras. The vote is widely being seen as determining whether the country should stay in the eurozone.

In the interview, Varoufakis reiterated a pledge to resign if the referendum resulted in a "yes."# Surveys have shown Greeks fairly evenly divided on how they will vote.

Tsipras on Friday spoke at a rally urging supporters to vote "no" in the referendum and "turn [their backs] on those who would terrorize you."

The prime minister is calling on creditors to forgive 30 percent of Greece's 323 billion euro debt and give the country a 20-year grace period for repaying the rest. Varoufakis has, however, denied reports that there are plans to seize 30 percent of bank deposits above 8,000 euros.